Method of manufacturing a web of continuous filaments



May 13, 1969 F. KALWAITES ET AL 3,443,284

METHOD OF MANUFACTURING A WEB OF CONTINUOUS FILAMENTS Filed May 21, 1965 INV NTORS:

561/5 7' a/m /rs ,ATTo NEY,

May 3, 1969 F. KALWAITES ET 4 METHOD OF MANUFACTURING A WEB OF CONTINUOUS FILAMENTS Filed May 21, 1965 Sheet 2 or z INVENTORS: flPA/VA Morn/res fe/va 1 l o/IP45 ATTORNEY United States Patent 3,443,284 METHOD OF MANUFACTURING A WEB OF CONTINUOUS FILAMENTS Frank Kalwaites, Somerville, and Ernest L. Poitras, Cranbury, N.J., assignors to Johnson & Johnson, a corporation of New Jersey Filed May 21, 1965, Ser. No. 457,643

Int. Cl. D01b 3/04 U.S. Cl. 19--66 5 Claims ABSTRACT OF THE DISCLOSURE A method of manufacturing a web of continuous filaments by passing a tow of filaments down an open inclined plane and flowing a liquid down the plane in a fan shaped pattern. The tow moves at a velocity slower than that of the liquid so that the diverging hydraulic forces of the liquid spread the tow into a web of filaments.

This invention relates to methods for manufacturing unitary webs; more particularly to methods of manufacturing fibrous webs of continuous synthetic textile filaments. These textile filaments are known man-made materials, being either artificial or synthetic in nature as hereinafter indicated, as distinct from natural fibers such as cotton, wool, etc. For convenience herein they will hereinafter be referred to as synthetic filaments and/or synthetic textile filaments.

As used herein the term web means a thin, flimsy, fibrous sheet of indefinite length as distinguished from ribbons or batts which have considerable thickness.

Heretofore, fibrous webs have been made from staple length fibers and/or short papermaking fibers, i.e., fibers less than about two inches in length. Such webs are made by a card engine or by papermaking or air-laying machines. These machines produce a thin sheet or web of overlapping, intersecting, randomly arranged fibers. The web is held together by the frictional entanglement of the fibers and is quite weak.

Nonwoven fabrics are produced from these prior art webs by playing a number of the webs together and applying an adhesive to the laminate to bond the same into a unitary structure.

The present invention contemplates a method for making a nonwoven unitary web of individual synthetic textile filaments. Each filament in the web has an irregular sinuosity throughout its length, thus presenting looped fiber portions which overlap and frictionally engage looped fiber portions of adjacent filaments of the web. The filaments are of substantially the same length, and the resulting web is of substantially uniform construction throughout its entire area. The unitary web will have a substantially uniform density and uniform covering properties, i.e., free of holes or thick areas.

Substantially all of the filaments lie in the same general direction and the nonwoven unitary webs made in accordance with the invention have considerable strength in the direction in which the filaments lie. Strong nonwoven fabrics may be produced by plying a number of these webs together, usually at angles to each other, and adding a small amount of adhesive to hold the plies together.

The present invention contemplates methods for producing nonwoven unitary webs from a tow of continuous synthetic filaments. These methods comprise presenting a tow of continuous synthetic filaments to an inclined plane having a liquid flowing down the plane in fan-shaped manner; any liquid which does not adversely affect the filament may be used; suitable examples are water, alcohol, etc. The tow and liquid move in the same direction 3,443,284 Patented May 13, 1969 but the velocity of the tow is slower than the velocity of the liquid. The fan-shape flow of liquid presents diverging hydraulic forces in the body of the liquid which open the tow and spread it into a thin web of continuous filaments. The thin web is presented to a condensing surface and the filaments therein become condensed or compacted lengthwise, in effect shortened lengthwise so that each filament assumes an irregular sinuous path. By effecting a substantially uniform lengthwise condensation of the filaments, the resulting web is of substantially uniform construction throughout its entire area. The resulting web is substantially free of voids, thin areas and thick areas and the filaments relatively uniformly cover the entire surface. The sinuous filaments present looped portions which overlap and entangle looped portions of adjacent filaments.

In spreading the tow of continuous filaments into a Web the filaments must be maintained under tension until the desired width of the web is attained. The tension may be obtained by the application of hydraulic forces to the tow as it is spread into a web. The hydraulic forces must be strong enough to part the slightly tangled filaments yet gentle enough so that they do not form either open places or conglomerations of filaments in the web. After the tow is spread into a web, the web is placed on a conveyor, moving at a relatively slower speed than the web, and the tension the filaments are under is thus released. This allows the filaments to take the configuration imparted to them by the differential in speed between the filaments and the conveyor.

When the tension is released the filaments fall in sinuous paths and form looped fiber portions which overlap and entangle looped fiber portions of adjacent filaments to form a nonwoven unitary web. The length of each individual filament in its irregular sinuous path is equal to the length of the web formed.

The invention will be further described in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a plan view of an apparatus for carrying out certain steps in the method of this invention,

FIGURE 2 is a side elevation view of the apparatus shown in FIGURE 1,

FIGURE 3 is a plan view of a nonwoven unitary web made by the method of the present invention,

FIGURE 4 is an enlarged cross-sectional view taken along line 44 of FIGURE 3. Referring to the drawings, in FIGURES 1 and 2 there is shown an apparatus for carrying out the method of the present invention. A bundle 20 of continuous filaments 21 having no definite twist (called a tow) is contmuously fed by a pair of nip rolls 22 and 23 through an orifice 24 onto an inclined plane 25. Liquid 26 is also fed through a nozzle 27 onto the same end of the inclined plane as the tow is fed. The tow and liquid move in the same direction, but the velocity of the tow is less than that of the liquid; the drag of the liquid on the slower moving tow pulls the tow through the orifice onto the plane.

The liquid is directed by the nozzle into a fan-shaped pattern as the liquid flows down the inclined plane. This may be readily done by the deflector plate 28 or by a nozzle designed to produce a fan-shaped pattern. If desired a number of streams of liquid may be used each producing a fan-shape pattern which overlap with adjacent streams to produce an integral fan-shape pattern. The fan-shape pattern of the liquid may vary from about a 30 degree angle to a degree angle but is preferably kept at approximately a 45 degree angle. The angle is of course dependent on the length of the inclined plane and the differential distance of travel between individual filaments. It is preferred that the liquid be directed onto a tow in order to get a uniform and thorough wetting of the tow. If desired and as shown the tow may be prewetted by placing a pan 30 of liquid under the nip rolls and wetting the tow prior to its being fed to the in clined plane. In some instances it may be preferable to prewet the tow with a surfactant or place a surfactant in the liquid to improve the wetting of the tow and improve the efficiency of spreading. This is especially true of some synthetic filaments, such as polyester filaments. Also in order to produce more uniform spreading a series of tows may be fed to the on'fice and spread simultaneously.

The liquid continually flows down the plane in a fan-shaped pattern at a velocity greater than the velocity at which the tow passes down the plane and thus maintains the tow under tension as it passes down the inclined plane. As the tow is fed onto the plane, the fan-shaped flowing liquid opens the tow and separates the continuous filaments. The tow is separated by the shear stress exerted by the liquid on the tow. This stress is in the same direction as the liquid velocity. The fan-shape flow provides a stress having a shear force component perpendicular to the centerline of the plane. This perpendicular force component spreads the tow as it passes down the plane. At the discharge end of the plane, the tow is in the form of a web 31 of continuous filaments and this web is placed on a continuous wire screen 32.

The upper reach of the wire screen passes from roller 33 closest to the plane to roller 34 spaced away from the plane and the lower reach from roller 34 to roller 33. As the spread tow contacts the screen, which is moving slower than the tow, the tension is released. The individual filaments fall in irregular sinuous paths on the screen, forming looped portions in the individual filaments, which overlap and entangle looped portions of adjacent filaments.

The screen with the spread tow (web) thereon passes over a suction box 35 to remove liquid therefrom. The web and screen then pass to a hot air drier 36 where the web of continuous filaments is dried. The irregular sinuous paths of the continuous filaments causes portions of filaments to overlap and frictionally engage portions of adjacent filaments to form a unitary web. The dried unitary web 37 may then be laminated with card, airlaid or other nonwoven fiber webs or with other spread tow webs to produce a fabric.

The liquid used is relatively unimportant in the spreading of tow provided the liquid has no adverse effects on the filaments. Economics, safety, ease of handling, etc., make the use of water one of the better liquids for the spreading of tow in accordance with the invention.

In some instances side panels may be placed on the inclined plane to prevent excessive overflow of liquid. When this is done care must be taken to prevent the side walls from interfering with the fanning of the liquid by producing eddy currents at the edges. This may be done by placing slits or perforations in the side walls.

Once the tow is spread into web form it is presented to the slower moving condensing surface of the wire screen. The differential in speed between the tow and the wire may be varied over wide ranges to impart various irregular sinuous paths to the filaments. This speed differential also governs the amplitude of the sinuous path of individual filaments in the web. Differentials in the speed of the tow and the speed of the wire in the range of from about 1.05 to 1 to 2:1 and even higher have given satisfactory results.

By the method of the invention tows ranging in diameter from of an inch up to about 1 inch or more and containing from 5,000 to 60,000 filaments or more may be spread to thin flimsy webs having weights ranging from about 25 grains per square yard up to about 200 grains per square yard or more.

In FIGURE 3 there is shown a nonwoven unitary web 41. The web comprises individual filaments 42 each of which lies in a sinuous path running in the direction of the length of the web. Looped or kinky portions of filaments overlap and entangle looped or kinky portions of adjacent filaments. Each individual filament in the web is at least as long as the length of the web formed. The web is very thin with the filaments 42 relatively uniformly distributed throughout the width of the web, as indicated in FIGURE 4.

The webs produced by the method of the invention may be produced from any of the known synthetic filaments, including artificial filaments. Suitable examples are viscose rayon, cuprammonium rayon, ethylcellulose, and cellulose acetate, i.e., nylon; polyesters, i.e., Dacron; acrylics, i.e., Orlon, Acrilan and Dynel; polyolefins, i.e., polyethylene, polypropylene; polyvinylidene chloride, i.e., saran; polyvinyl chloride, polyurethanes, etc. These synthetic filaments may be used alone or in combination with one another.

The weight of the webs range from about 25 grains per square yard to 200 grains per square yard and preferably from about 35 grains per square yard to grains per square yard.

The denier of the filaments used to produce the web is in the range of from about 1 denier and somewhat less to about 10 denier. It is preferred that the filaments have a denier in the range of from about 1 /2 to 6. For example, viscose rayon filaments from about 1 /2 to 3 denier have produced excellent results in the production of the fabrics according to the invention.

Filaments having a denier above the indicated broad range are stiff and rigid and will not lie in irregular sinuous paths uniformly throughout the web. The fabrics produced from webs of such high denier filaments are not drapeable textile fabrics having a silk-like softness as contemplated herein, but are rigid and harsh and unsuitable for use in surgical dressings, sanitary napkins and the like.

The invention will be further illustrated in greater detail by the following specific example. The percentages indicated are by weight unless specifically stated otherwise.

Example A viscose rayon tow approximately of an inch in diameter, 6,000 denier, and containing 2,934 individual continuous filaments of about 2 denier per filament is fed by a pair of nip rolls down an inclined plane at the rate of approximately 40.5 feet per minute. The inclined plane is 27 inches long and 26 inches wide. A flow of water is maintained down the plane in fan-shaped manner, the fan angle being approximately 45 degrees. The water velocity down the plane is approximately 395 feet per minute.

The tow passes through the entry hole onto the plane and the flow of water pulls the tow down the plane. The fan-shape flow of water causes the filaments to spread in a fan-shaped pattern. The tow is removed from the discharge end as a substantially uniform sheet of continuous filaments 20 inches wide. 'Ihese filaments are discharged onto a wire screen passing over a suction box. The screen is moving at 38% feet per minute. The suction box removes the water from the continuous filament sheet and the reduced speed of the wire causes the individual filaments to lie in irregular, sinuous paths and form looped portions which overlap and entangle looped portions which overlap and entangle looped portions of adjacent filaments.

The sheet on the screen is passed under a spray of approximately 1% polyvinyl alcohol solution and over a second suction box to remove more water from the sheet. The sheet is then passed under a hot air dryer to remove the remainder of the water and the dry sheet rolled on a core. The nonwoven unitary base web produced is approximately 20 inches wide and weighs 56 grains per square yard.

Although a specific example of the inventive concept has been described for purposes of illustration, the invention should not be construed as limited thereby nor to the specific features mentioned therein except as the same may be included in the claims appended hereto. It is understood that changes, modifications and variations may be made in the fabric and the method herein described without departing from the spirit and scope of the claimed invention.

What is claimed is:

1. A method of producing a nonwoven unitary web of continuous synthetic filaments which comprises: presenting a tow of continuous synthetic filaments to an open inclined plane, flowing a liquid down said plane in a fanshape pattern while conveying said tow in the liquid in the same direction that the liquid is moving and at a velocity slower than that of the liquid whereby diverging hydraulic forces are applied to said tow while it is being conveyed in said liquid whereby the tow is spread into a thin web of continuous synthetic filaments.

2. A method of producing a nonwoven unitary web of continuous synthetic filaments which comprises: presenting a tow of continuous synthetic filaments to an open inclined plane, flowing the liquid down said plane in a fanshape pattern while conveying said tow in the liquid in the same direction that the liquid is moving and at a velocity slower than that of the liquid whereby diverging hydraulic forces are applied to said tow While it is being conveyed in said liquid and the tow is spread into a thin web of continuous synthetic filaments and uniformly compacting said Web in a lengthwise direction whereby the filaments assume irregular sinuous paths and present looped portions which overlap and entangle looped portions of adjacent filaments to form a unitary web.

3. A method of producing a nonwoven unitary web of continuous synthetic filaments which comprises; presenting a tow of continuous synthetic filaments to an open inclined plane, flowing a liquid down said plane in a fanshape pattern while conveying said tow in the liquid in the same direction that the liquid is moving and at a velocity slower than that of the liquid whereby diverging hydraulic forces are applied to said tow while it is being conveyed in said liquid and the tow is spread into a thin web of continuous synthetic filaments and presenting said web of continuous synthetic filaments to a surface moving away from said liquid and at a speed slower than the speed of said web in the liquid whereby a thin web of continuous synthetic filaments each having an irregular sinuosity is formed.

4. A method of producing a nonwoven unitary web of continuous synthetic filaments which comprises: presenting a tow of continuous synthetic filaments to an open inclined plane, flowing water down said plane a fan-shape pattern while conveying said tow in the water in the same direction that the water is moving and at a velocity slower than that of the water, whereby diverging hydraulic forces are applied to said tow while it is being conveyed in the water whereby the tow is spread into a thin web of continuous synthetic filaments and uniformly compacting said web in a lengthwise direction whereby the filaments assume irregular sinuous paths and present looped portions which overlap and entangle looped portions of adjacent filaments to form a unitary web and drying said unitary web to remove the water.

5. A method of producing a nonwoven unitary web of continuous synthetic filaments which comprises: presenting a tow of continuous synthetic filaments to an open inclined plane, flowing water down said plane in a fan-shape pattern of approximately degrees while conveying said tow in the water in the same direction that the water is moving and at a velocity slower than that of the water where diverging hydraulic forces are applied to said tow 'while it is being conveyed in the water whereby the tow is spread into a thin web of continuous synthetic filaments and uniformly compacting said web in a lengthwise direction whereby the filaments assume irregular sinuous paths and present looped portions which overlap and entangle looped portions of adjacent filaments to form a unitary web and drying said unitary web to remove the water.

References Cited UNITED STATES PATENTS DORSEY NEWTON, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,443,284 May 13, 1969 Frank Kalwaites et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 43, "playing" should read plying Column 4, line 63, cancel "which overlap and entangle looped portions". Column 6, line 8, after "plane" insert in line 39, "2,981,895" should read 2,981,985

Signed and sealed this 28th day of October 1969.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer WILLIAM E. SCHUYLER, IR.

Commissioner of Patents 

